Double Rayleigh Backscattering Noise Research Articles

Studying the Double Rayleigh Backscattering Noise Effect on Fiber-Optic Radio Frequency Transfer

We report the effect of the double Rayleigh backscattering (DRB) noise, in which the interference of the signal light with the double Rayleigh backscattered light, on the fiber-optic radio-frequency (RF) transfer system. Here, we theoretically analyze and experimentally demonstrate that the DRB noise within the fiber link will become the dominative noise on the fiber-optic RF transfer system once narrow linewidth lasers are used. The strong DRB noise is experimentally confirmed through the measurement of the effect of the coherent interference term of the signal light and the double Rayleigh backscattered light on the 100 km RF transfer system. Our results provide evidence that the conventional RF transfer technique with the telecommunications-grade lasers, in which the chromatic dispersion effect in the single-mode fiber is compensated by dispersion compensation fibers (DCFs), could be the better choice for high-performance RF transfer.

Research on the [formula omitted]-OTDR fiber sensor sensitive for all of the distance

In this paper, a modified construction for the traditional ϕ-OTDR fiber sensor sensitive for all of distance is presented, the related numerical simulation and experiment analysis results show that this construction can reduce the gain imbalance for all of the distance along the fiber caused by the Rayleigh scattering loss of the fiber and the gain imbalance of Raman fiber amplifier in this fiber sensor system. In order to improve further the vibration sensitivity of this system, the possible methods to restrain the influences of modulation instability effect, Stimulated Brillouin effect, reduce the amplified spontaneous emission (ASE) noises of Raman laser (RL) and Erbium3+-doped fiber amplifiers (EDFA), double Rayleigh backscattering noise in this system are discussed, which will offer a great reference value for the science research and engineering application in the field of fiber sensor as we believe.

Performance of DRA with different pumping schemes based on coupling equation

After the coupling equations of co-pumping, counter-pumping and bidirectional-pumping distributed Raman amplifiers (DRAs) are theoretically analyzed, the power distributions of these three DRAs are acquired with numerical analysis. The performance factors, such as net gain (NG), amplified spontaneous emissions (ASE) noise, double Rayleigh backscattering (DRB) noise, noise figure (NF) and optical signal noise ratio (OSNR), are discussed in depth. It can be found that the NGs of the three DRAs are almost equal. The counter-pumping scheme will induce higher ASE. And the co-pumping DRA has greater DRB noise, but its NF and OSNR are both better than the others’. Furthermore, the relations between signal power and NG, NF, OSNR are also investigated. It is shown that the NF and OSNR of the co-pumping scheme are superior to those of the other two schemes at small input signal power. The above conclusions can play a very important role in guiding the optimum design of DRA.

Analytical Design, Analysis, and Optimization of Raman Fiber Amplifiers With TDM Pumps

In this paper, we analyze Raman amplifiers (RAs) with time division multiplexed (TDM) pumps via an analytical approach. First of all, a detailed analytical solution for the forward and backward propagating waves in the TDM-pumped RAs is presented. Then, the gain of the TDM-pumped RAs is treated analytically. After revealing the nature of resonant gain enhancement, a relatively simple formula of the optimal input pump power configuration is derived via the least squares method. Afterwards, enhanced double Rayleigh backscattering noise and amplified spontaneous emission noise are analyzed and explicit analytical formulas derived. Thereafter, a simple formula to evaluate the impact of the pump modulation is proposed for the design, analysis, and optimization. The analysis of the TDM-pumped RAs highlights the optimization of the parameters of the TDM pumps, such as the pump wavelengths, pump power, and pump modulation frequency as well as the pumping order.

Low-Noise Fiber Raman Amplifiers Based on a Raman Ring Fiber Oscillator

We propose two discrete fiber Raman amplifier schemes using Raman ring fiber oscillator, a two-stage scheme, and a forward pumping scheme, to reduce double Rayleigh backscattering noise at high gains over 20 dB. Both schemes have low noise characteristics compared to a previous scheme. Bit-error-rate measurements at 10 Gb/s show power penalty free operation for the two-stage scheme at a gain of 25 dB.

Bit-Error-Rate Evaluation of the Distributed Raman Amplified Transmission Systems in the Presence of Double Rayleigh Backscattering Noise

A new exact bit-error-rate evaluation method for distributed Raman amplification transmission systems in the presence of both amplified spontaneous emission and double Rayleigh backscattering (DRB) is developed based on a study of statistical characterization of DRB

An Optimization Process for Hybrid Dual-Stage Raman/EDF Amplifiers When Kerr-Nonlinearity, Double Rayleigh Backscattering Noise and OSNR are Important

In this paper, a detailed model of a hybrid dual-stage Raman/erbium-doped fiber (EDF) amplifier is presented. This model takes into account the impact of double Rayleigh backscattering (DRB) noise, amplified spontaneous emission (ASE) noise and Kerr-nonlinearity induced impairments in the amplification process. Using this model, we present a comprehensive analysis of the operation of hybrid dual-stage Raman/EDF amplifiers under above impairments. We show that under fixed total gain conditions for the amplifier module, high Raman gain causes the introduction of increased DRB noise to the amplified signals whereas low Raman gain causes the introduction of high ASE noise power through EDF amplifier. Therefore a balance between the Raman amplifier gain and EDF amplifier gain is required for optimal operation. These observations are then combined to show an optimization process, which could be applied to improve the design of hybrid dual-stage Raman/EDF amplifiers.

Optimal Position of Isolator to Suppress Double Rayleigh Backscattering Noise in Fiber Raman Amplifiers

In this paper, amplified double Rayleigh backscattering noise (DRB) in the optical fiber Raman amplifier is analyzed. Expressions are present for both forward pumping and backward pumping schemes, respectively. Calculation is performed to show the effective suppression of DRB noise by employing an optical isolator. The best isolator position is determined as 13 km away from the signal input end for forward pumping, and 9 km from the output end for backward pumping. The best position is found insensitive to the fiber length, pump power, and signal power. When the isolator is on the best position, the DRB noise can be reduced by almost 2 to 3 orders.

Theoretical analysis on double Rayleigh backscattering noise in optical fibre Raman amplifiers and its suppression

In this paper, amplified double Rayleigh backscattering noise (DRB) in the optical fibre Raman amplifier is analysed. Expressions are presented for both forward pumping and backward pumping schemes. Calculation is performed to show the effective suppression of DRB noise by employing an optical isolator. The optimal position for the isolator is determined and is found to be insensitive to the power levels of the signals and pumps. The results show that a reduction of the DRB noise by almost 2 to 3 orders can be reached.

Comparison of different Raman amplification schemes in long-span fiber transmission systems with double Rayleigh backscattering

In this letter, three Raman amplification configurations, which are bidirectional pumping scheme, backward pumping with mid-way isolators, and Raman plus erbium-doped fiber amplifier hybrid amplification, respectively, are optimized and compared in long-span (> 120 km) transmission systems including the impacts of double Rayleigh backscattering (DRB). Numerical results show that a balanced bidirectional pumping scheme can achieve the best performance for most practical conditions at identical nonlinearity. However, hybrid amplification will be a better choice when DRB noise is overwhelming.